Field of the Invention
The present invention relates to a metal nitride material for a thermistor, which can be directly deposited on a film or the like without firing, a method for producing the same, and a film type thermistor sensor.
Description of the Related Art
There is a demand for a thermistor material used for a temperature sensor or the like having a high B constant in order to obtain a high precision and high sensitivity thermistor sensor. Conventionally, oxides of transition metals such as Mn, Co, Fe, and the like are typically used as such thermistor materials (see Patent Documents 1 and 2). These thermistor materials need firing at a temperature of 600° C. or higher in order to obtain a stable thermistor characteristic/property.
In addition to thermistor materials consisting of metal oxides as described above, Patent Document 3 discloses a thermistor material consisting of a nitride represented by the general formula: MxAyNz (where “M” represents at least one of Ta, Nb, Cr, Ti, and Zr, “A” represents at least one of Al, Si, and B, 0.1≦x≦0.8, 0<y≦0.6, 0.1≦z≦0.8, and x+y+z=1). In Patent Document 3, only a Ta—Al—N-based material consisting of a nitride represented by the general formula: MxAyNz (where 0.5≦x≦0.8, 0.1≦x≦0.5, 0.2≦z≦0.7, and x+y+z=1) is described in an Example. The Ta—Al—N-based material is produced by sputtering in a nitrogen gas-containing atmosphere using a material containing the element(s) listed above as a target. The resultant thin film is subject to a heat treatment at a temperature from 350 to 600° C. as required.
Other than thermistor materials, Patent document 4 discloses a resistance film material for a strain sensor, which consists of a nitride represented by the general formula: Cr100-x-yNxMy (where “M” is one or more elements selected from Ti, V, Nb, Ta, Ni, Zr, Hf, Si, Ge, C, O, P, Se, Te, Zn, Cu, Bi, Fe, Mo, W, As, Sn, Sb, Pb, B, Ga, In, Tl, Ru, Rh, Re, Os, Ir, Pt, Pd, Ag, Au, Co, Be, Mg, Ca, Sr, Ba, Mn, Al, and rare earth elements, the crystal structure thereof is composed of mainly a bcc structure or mainly a mixed structure of a bcc structure and A15 type structure, 0.0001≦x≦30, 0≦y≦30, and 0.0001≦x+y≦50). The resistance film material for a strain sensor is employed for measuring strain and stress from changes in the resistance of the sensor made of a Cr—N-based strain resistance film, where both of the amounts of nitrogen (x) and an accessory component element(s) M (y) are 30 at % or lower, as well as for performing various conversions. The Cr—N-M-based material is produced by reactive sputtering in a deposition atmosphere containing the accessory gaseous element(s) using a material containing the above-described element(s) or the like as a target. The resultant thin film is subject to a heat treatment at a temperature from 200 to 1000° C. as required.